scholarly journals Scalar Field Models for an Accelerating Universe

2005 ◽  
Vol 201 ◽  
pp. 260-263
Author(s):  
Varun. Sahni
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Cold Dark Matter ◽  
High Redshift ◽  
Accelerating Universe ◽  
Late Time ◽  
Luminosity Distance ◽  
New Class ◽  
Scalar Field Models ◽  
Model Independent

I describe a new class of quintessence+CDM models in which late time scalar field oscillations can give rise to both quintessence and cold dark matter. Additionally, a versatile ansatz for the luminosity distance is used to reconstruct the quintessence equation of state in amodel independentmanner from observations of high redshift supernovae.

scholarly journals CONSTRAINING TEVES GRAVITY AS EFFECTIVE DARK MATTER AND DARK ENERGY

2007 ◽  
Vol 16 (12a) ◽  
pp. 2055-2063 ◽  
Author(s):  
HONGSHENG ZHAO
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Gravitational Lensing ◽  
Cold Dark Matter ◽  
High Redshift ◽  
Elliptical Galaxies ◽  
Dual Roles ◽  
Acceleration Of The Universe ◽  
The Universe

The phenomena customarily described with the standard ΛCDM model are broadly reproduced by an extremely simple model in TeVeS, Bekenstein's1 modification of general relativity motivated by galaxy phenomenology. Our model can account for the acceleration of the Universe seen at SNeIa distances without a cosmological constant, and the accelerations seen in rotation curves of nearby spiral galaxies and gravitational lensing of high-redshift elliptical galaxies without cold dark matter. The model is consistent with BBN and the neutrino mass between 0.05 eV to 2 eV. The TeVeS scalar field is shown to play the effective dual roles of dark matter and dark energy, with the amplitudes of the effects controlled by a μ function of the scalar field, called the μ essence here. We also discuss outliers to the theory's predictions on multiimaged galaxy lenses and outliers on the subgalaxy scale.

scholarly journals Smooth Crossing ofwΛ=−1Line in a Single Scalar Field Model

2009 ◽  
Vol 2009 ◽  
pp. 1-14 ◽  
Author(s):  
Abhik Kumar Sanyal
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Cosmological Model ◽  
Simple Form ◽  
Cold Dark Matter ◽  
Field Model ◽  
Late Time ◽  
Transient Phenomenon ◽  
Phantom Divide ◽  
Phantom Divide Line

Smooth double crossing of the phantom divide linewΛ=−1has been found possible with a single minimally coupled scalar field for the most simple form of generalizedk-essence cosmological model, in the presence of background cold dark matter. Such crossing is a sufficiently late time transient phenomenon and does not have any pathological behaviour.

On the late-time cosmology of a condensed scalar field

2016 ◽  
Vol 31 (12) ◽  
pp. 1650078
Author(s):  
Amir Ghalee
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Condensed Phase ◽  
Cold Dark Matter ◽  
Accelerated Expansion ◽  
Kinetic Term ◽  
Late Time ◽  
Gradient Instability

We study the late-time cosmology of a scalar field with a kinetic term non-minimally coupled to gravity. It is demonstrated that the scalar field dominate the radiation matter and the cold dark matter (CDM). Moreover, we show that eventually the scalar field will be condensed and results in an accelerated expansion. The metric perturbations around the condensed phase of the scalar field are investigated and it has been shown that the ghost instability and gradient instability do not exist.

scholarly journals Holographic cosmology with two coupled fluids in the presence of viscosity

2021 ◽  
pp. 2150149
Author(s):  
I. Brevik ◽  
A. V. Timoshkin
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Holographic Dark Energy ◽  
Exponential Model ◽  
Point Of View ◽  
Accelerating Universe ◽  
Late Time ◽  
Conservation Of Energy ◽  
Analytical Expressions ◽  
Friedmann Robertson Walker

We explore the cosmological models of the late-time universe based on the holographic principle, taking into account the properties of the viscosity of the dark fluid. We use the mathematical formalism of generalized infrared cutoff holographic dark energy, as presented by Nojiri and Odintsov [Covariant generalized holographic dark energy and accelerating universe, Eur. Phys. J. C 77 (2017) 528]. We consider the Little Rip, the Pseudo Rip, and a bounce exponential model, with two interacting fluids, namely dark energy and dark matter in a spatially-flat Friedmann–Robertson–Walker universe. Within these models, analytical expressions are obtained for infrared cutoffs in terms of the particle horizons. The law of conservation of energy is presented, from a holographic point of view.

INTERACTING GENERALIZED DARK ENERGY AND RECONSTRUCTION OF SCALAR FIELD MODELS

2013 ◽  
Vol 28 (38) ◽  
pp. 1350180 ◽  
Author(s):  
M. SHARIF ◽  
ABDUL JAWAD
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Dark Energy Model ◽  
Cold Dark Matter ◽  
Scalar Potential ◽  
Scalar Fields ◽  
Phantom Divide ◽  
Evolution Parameter ◽  
Scalar Field Models ◽  
Phantom Divide Line

In this paper, we consider the interacting generalized dark energy with cold dark matter and analyze the behavior of evolution parameter via dark energy and interacting parameters. It is found that the evolution parameter crosses the phantom divide line in most of the cases of integration constants. We also establish the correspondence of scalar field models (quintessence, k-essence and dilaton) with this dark energy model in which scalar fields show the increasing behavior. The scalar potential corresponds to attractor solutions in quintessence case.

Are Simulations of Cold Dark Matter Consistent with Galactic-Scale Observations at High Redshift?

2001 ◽  
Vol 560 (1) ◽  
pp. L33-L36 ◽  
Author(s):  
Jason X. Prochaska ◽  
Arthur M. Wolfe
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
High Redshift

scholarly journals Small-scale Substructure in Dark Matter Haloes: Where Does Galaxy Formation Come to an End?

2004 ◽  
Vol 220 ◽  
pp. 91-98 ◽  
Author(s):  
J. E. Taylor ◽  
J. Silk ◽  
A. Babul
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Structure Formation ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
High Redshift ◽  
Small Scale ◽  
Analytic Model ◽  
Model Predictions ◽  
Low Mass

Models of structure formation based on cold dark matter predict that most of the small dark matter haloes that first formed at high redshift would have merged into larger systems by the present epoch. Substructure in present-day haloes preserves the remains of these ancient systems, providing the only direct information we may ever have about the low-mass end of the power spectrum. We describe some recent attempts to model halo substructure down to very small masses, using a semi-analytic model of halo formation. We make a preliminary comparison between the model predictions, observations of substructure in lensed systems, and the properties of local satellite galaxies.

scholarly journals CAN BRANS–DICKE SCALAR FIELD ACCOUNT FOR DARK ENERGY AND DARK MATTER?

2006 ◽  
Vol 21 (15) ◽  
pp. 1241-1248 ◽  
Author(s):  
M. ARIK ◽  
M. C. ÇALIK
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Energy Density ◽  
Late Time ◽  
Energy Contribution ◽  
Time Solution ◽  
The Universe

By using a linearized non-vacuum late time solution in Brans–Dicke cosmology, we account for the 75% dark energy contribution but not for approximately 23% dark matter contribution to the present day energy density of the universe.

scholarly journals Brief History of Ultra-light Scalar Dark Matter Models

2018 ◽  
Vol 168 ◽  
pp. 06005 ◽  
Author(s):  
Jae-Weon Lee
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Cold Dark Matter ◽  
Einstein Condensate ◽  
Matter Wave ◽  
Small Scale ◽  
Matter Model ◽  
Light Scalar ◽  
History Of ◽  
Dark Matter Model

This is a review on the brief history of the scalar field dark matter model also known as fuzzy dark matter, BEC dark matter, wave dark matter, or ultra-light axion. In this model ultra-light scalar dark matter particles with mass m = O(10-22)eV condense in a single Bose-Einstein condensate state and behave collectively like a classical wave. Galactic dark matter halos can be described as a self-gravitating coherent scalar field configuration called boson stars. At the scale larger than galaxies the dark matter acts like cold dark matter, while below the scale quantum pressure from the uncertainty principle suppresses the smaller structure formation so that it can resolve the small scale crisis of the conventional cold dark matter model.

Sign in / Sign up

Export Citation Format

Share Document